feat(provider): 增加 Claude Code 适配器、高级配置能力与 OAuth 账号类型统一解析

- 新增 Claude Code provider adapter (context, envelope, plugin, constants)
- 扩展 provider admin 路由，支持 Claude Code 高级配置 (CRUD)
- 统一 OAuth 账号类型解析逻辑，前后端对齐
- 重构 BatchAssignModelsDialog / ModelMappingDialog，简化组件逻辑
- handler 基类增强: request_builder 支持 Claude Code 信封格式
- CLI stream/sync mixin 适配 Claude Code 流式与同步模式
- 扩展 candidate builder / failover / scheduler 对 Claude Code 的支持
- 前端增加请求时间线可视化 (HorizontalRequestTimeline)
- 补充 Claude Code envelope / runtime controls / distributed sessions 等测试

Closes #183
Closes #185

Co-Authored-By: AAEE86 <ppk0227@hotmail.com>

tests/services/test_candidate_resolver_pagination.py

@@ -30,6 +30,7 @@ class _FakeScheduler:
         max_candidates: int | None = None,
         is_stream: bool = False,
         capability_requirements: dict[str, bool] | None = None,
+        request_body: dict | None = None,
     ) -> tuple[list[Any], str, int]:
         _ = (
             db,